Virtual Reality (VR) typically employs computer-generated stimulation of the human sensorium to simulate naturally occurring inputs such as sight and sound. Additional senses which may be stimulated include orientation, balance, and touch and force (haptic) feedback. A complete and immersive VR experience might simultaneously stimulate a user with sight, sound, touch, and movement.
A major limitation in state-of-the-art VR is the inability to permit simple walking and running. Navigation is typically experienced as a disembodied center of consciousness which is directed by pointing, other gesture or by manipulation of a joystick, trackball, mouse, or similar device. The actual physical sensation of walking is limited to one of two forms: a) The user is restricted to a confined and immobile surface where tracking and signal generation are well-controlled, and b) the user is confined to a device such as a linear treadmill or wheelchair which transduces the user's linear motion from real space to virtual space. The conventional linear treadmill has a movable track which may optionally be upwardly inclined. The track is only movable in one direction which restricts motion of the user to the direction of movement of the track. A monitor, such as a motivational electric display, associated with the track, records the time, speed, and distance accomplished by the user.
Use of a linear treadmill in a virtual environment consists of, one continuous moving track, and in conjunction with an external monitor or head mounted-display permits a user to walk in a straight line. The user cannot step in arbitrary directions as s/he would be able to in real life. This limitation in navigation detracts from the immersive nature of the experience, and requires that the experience takes on more of a vehicular nature rather than that of a freely walking and navigating body.